Process for imparting to wool a gloss similar to that of natural silk



Patented Apr. 17, 1945 PROCESS .FOR

IMPARTING TO WOOL A GLOSS SIMILAR TO THAT OF NATURAL SILK Henry Phillips, William Robert Middlebrook, and

Alfred Edward Hig gins, Leeds, England, as-

signors to Wool Industries Research Association, Leeds, England No Drawing. Application December 30, 1941, Se-

rial No. 425,008. In Great Britain February 7, 1941 12 Claims.

This invention relates to the treatment of wool, or wool materials, or materials containing wool, in the form of loose fibres or in a manufactured form such as yarn and fabric, whereby the wool acquires a silk-like gloss and appearance and may also acquire a scroopy handle or feel which can be accentuated by treatments which are known to accentuate the scroopy handle or feel of natural silk.

It is well known that when wool is treated with water containing chlorine or with acidified solutions of salts of hypochlorous acid the wool shows a diminished tendency to felt and, when the treatment has been sufliciently intense, has a silk-like gloss. Such processes are diflicult to control and may result in uneven treatment and serious weakening of the Wool. In addition, wool treated in this manner tends to have a harsh handle or feel.

In British Patent No. 11,917 of 1897, a process is described for treating wool with chlorine gas to give the wool a silk-like gloss, 'and wool treated with chlorine gas as described in British Patent No. 417,719 is said to have a distinctive silky appearance. In both these processes the degree of silk-like gloss imparted to the wool is dependent on the moisture content of the wool when it is treated with the chlorinegas; the higher the moisture content of the wool, the higher being the degree of silk-like gloss imparted to the wool. The treatment of moist wool with chlorine gas is difficult to control, since the heat generated by the reaction of the wool with the chlorine gas causes evaporation and migration of the moisture to the cooler portions of the wool, so that irregular treatment and possibly damage to the wool may result. On the other hand, the treatment of dry wool, or wool containing not more than 9 per cent of moisture, with chlorine gas proceeds smoothly, but although the treated wool shows a diminished tendency to felt, it is not glossy like silk and may be less attractive than the original wool. It has been proposed to treat wool with other substances, either as vapors or dissolved in organic solvents. to diminish the tendency of wool to felt. These substances include sulphuryl chloride (British Patent No. 464,- 503), organic hypochlorites (United States Patents Nos. 2,132,342 and 2,132,345) and nitrosyl chloride (United States Patent No. 2,213,399). Wool treated with these substances, however, has not the gloss and scroop of natural silk.

We have discovered, and this discovery forms the basis of our invention, that wool which has been treated to diminish its tendency to felt,

preferably treated with a non-aqueous agent which diminishes its tendency to felt, for example, chlorine gas, sulphuryl chloride or the like,

can be caused to acquire the silk-like gloss, scroop and soft handle of natural silk by treating it with a solution of the vegetable protease papain, either alone or preferably in the presence of one or more substances (hereinafter referred to as accelerators) which'are known to increase the susceptibility of wool to the action of papain,

In British Patent No. 513,919 a process is described-for treating wool with a solution of a vegetable protease, such as papain, with or without the addition of a substance which increases the susceptibility of the wool to the action of papain, in order to diminish the tendency of the wool to felt when washed. In carrying out this process, the duration of treatment of the wool must be limited so that the wool suffers the minimum loss in weight consistent with the desired degree of diminution of the tendency to felt. Prolongation of the treatment utimately causes the wool to disintegrate and at no stage in the treatment does it acquire a silk-like gloss. Furthermore, the treated wool does not possess the scroopy handle of natural silk; if the treatment is prolonged beyond a certain stage, the wool loses its characteristic wool handle and ac-' quires a handle similar to that of cotton.

In the process of the present invention, wool is given the gloss of silk by treating with a so-' Lil lution of papain containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment, not a normal scoured and feltable wool but a wool that has already been treated, While containing not more than 9 per cent of moisture, to diminish its tendency to felt by a process involving the use, not of a vegetable protease, but of a non-aqueous agent selected from the group consisting of chloine gas, sulphuryl chloride, organic hypochlorites and nitrosyl chloride. Such wool previously treated with a non-aqueous agent as aforesaid will be referred to hereinafter as non-felting wool.

It is believed, although this does not limit this I ilar to that of degummed silkflbres; the treated wool fibres are free-from scales whilst the cortical;

prefer ably be made non-feltingby treating it whilst containing'l-B per cent of mots--- ture, with chlorinegas. After mistreatment, it 1 is neutraliz'ed withfadilute solution of sodium .cells of the fibres remai'nimrisible- To achieve the desired result within a convenient period of time we have found that the pH of the papain solution should be in the near neighborhood of about 0.025 per cent, the wool/liquor ratio pref- ,erably about 1:15, and-the temperature of the solution between 50-65 0.; furthermore, the solution should contain an accelerator, the concentration of which should preferably be about 0.25 per cent calculated :on the weightof the enzyme solution. The optimum concentration of the ac celerator will depend in part on the degree of treatment which the wool has received to render it non-felting, the higher the degree of treatment the greater being the quantity of altered wool substance on the surface of the fibres and hence the higher the concentration of accelerator or accelerators required to render it susceptible to the action of the papain. It is, however, advisable maintain the concentration of the accelerator or accelerators as low as possible in order to reduce to a minimum the action of the papain on the unaltered wool substance. In the absence ofany accelerator the process may be inconveniently long and may occupy, for instance, about 24 hours.

When the wool has received a high degree of 3 treatment to render it non-felting, a higher tem- 5.0, the concentration of the papain solution sesquicarbonate and then circulated through a solution containing 0.25 per cent of sodium'bisulphite and 0.25 per cent of sodium acetate, the

pH of this solution being adjusted to and maintained at 5.0 .by the addition of the requisite amount of acetic acid; When the pH of the solution remains constant at 5.0 the papain is addedandthe temperature is raised to 65 C. After perature, that is, a temperature more nearly approaching 65 C., is desirable. Increase of the concentration of the papain beyond 0.025 per cent on the weight of the liquor is, however, unlikely to hasten the process. When the pH of the papain solution falls below the 5.0 the process becomes slower, whilst when the pH of the papain solution rises above 5.0, the rate of the action of the papain solution on the unaltered wool substance increases, particularly when the solution contains an accelerator. It is therefore an advantage to add to the papain solution an electrolyte or electrolytes selected from the group of buifer substances or buffer mixtures in order to maintain a constant hydrogen ion concentration in the solution. Suitable electrolytes are acetic acid, sodium sesquicarbonate, sodium acetate, sodium dihydrogen phosphate and the like, or mixtures of these electrolytes.

The preferred accelerator is sodium bisulphite, but other substancesknown to activate papain and also to react with disulphide linkages believed to exist in wool can be used instead of sodium bisulphite, such as hydrogen sulphide, hydrocyanic acid and its water-soluble salts, or water-soluble mercaptans and thiol acids and their salts, or sodium thiosulphate or sodium hydrosulphite. Cysteine may also be used and may be added either as such or in the form of cystine, or cystine mixed with other amino-acids, as is obtained by the hydrolysis of wool with aqueous hydrochloric acid.

An advantage of the use of sodium bisulphite is that the solution has a bleaching action on the non-felting wool and the bleach obtained is more permanent to the action of alkaline washing liquors than the bleach normally obtained by the action of a solution of sodium bisulphite on wool. or on wool which has been treated to diminish its tendency to felt.

By the process of the invention the handle of the finished wool fabric can be varied within wide limits. If a wool fabric is desired with both a silky appearance and scroopy handle, it should about 2 hours, the wool is rinsed with water and then with an aqueous solution of a substance known to enhance the scroop of natural silk, especially an organic acid, such as acetic, formic, tartaric or citric acid. or with a solution of sodium hexametaphosphate, which, as we have found, also has the effect of enhancing the scroop of the treated wool. If a pronounced scroop is desired, the wool fabric which, after treatment with papain, has been rinsed in a dilute solution of sodium sesquicarbonate may be saturated with a soap solution and then milled in milling stocks. After the soap has been rinsed out of the milled but unfelted fabric, the fabric can be treated as above described with an aqueous solution of sodium hexametaphosphate or of a substance known to increase the scroop of natural silk. Alternatively, the non-felting wool fabric may be treated in a milling machine with the solution of papain, with or without an accelerator and after neutralization milled in soap.

If it is desired to impart to the wool fabric a silky appearance without the scroopy handle of silk, the fabric should be rinsed in a solution of sodium sesquicarbonate or similar alkali after the treatment with papain, lightly milled with soap, rinsed without attempting to remove all the soap and pressed whilst still damp. In the case of wool in the form of loose wool or top, similar efiects can be produced by passing the wool, after the treatment with papain, through a solution of sodium sequicarbonate or a similar alkali then through a solution of soap and finally through water, the wool being passed through squeeze rollers before and after passage through the soap solution and the water. Wool in the form of yarn can be treated in a similar manner following the treatment with papain. I

The process may be advantageously applied to fine wools when it is desired to make them completely non-felting in addition to giving them a gloss and scroop similar to that of natural silk.

'' It is sometimes found that it is difllcult to render fabrics made from such wools completely nonfelting by the use of chlorine gas, sulphuryl chloride or the like, without impairing their soft handle, since such fabrics require more profound as cotton and rayon, since cellulosic fibres are substantially unchanged by treatment with solutions of papain containing sodium bisulphite.

When solutions of papain containing sodium bisulphite are used to treat non-felting wool materials containing scoured (de-gummed) silk, the silk is substantially unaffected. When solutions of papain containing sodium bisulphite are used to treat non-felting wool materials containing raw silk, the layer of bast" surrounding the real and valuable fibroin filaments of the silk is attacked and is partially or wholly removed.

The following examples illustrate the invention; the parts are by weight:

Example 1 with 2000 parts of a solution containing parts of sodium bisulphite and 5 partsof sodium acetate. This liquor was circulated through the tops and acetic acid was added to bring its pH value to 5.0. A strong emulsion containing 0.5 part of commercial papain was then added to the liquor. the liquor was heated to 65 C. and circulated through the tops for 2 hours, after .which it was replaced by a tepid dilute solution of sodium sesquicarbonate. The tops were finally rinsed in, water containing sodium hexametaphosphate,.

in appeardrid and re-gilled. They were silky ance and had a scroopy handle.

Example 2 Unsecured yarn in oil (2/32s, 70s quality, 100

parts) was dried in hank form until it contained 7 per cent of moisture and then treated with chlorine gas as described in British Patent No.

417,719 or No. 475,742. The non-felting yarn obtained was neutralized with a solution of sodium sesquicarbonate and then scoured. The scoured yarn was treated in a Husson dyein machine with a solution (5,000 parts) containing commercial papain (1.25 parts) sodium bisulphite (12.5 parts) and sufficient acetic acid to bring the pH of the I solution to 5.0 whilst in contact with the wool.

The solution was heated to C. and then cir- Example 3 An unscoured worsted fabric parts) of 64s wool was dried until it contained 7 per cent of moisture and was then treated with chlorine as as described in British Patent No. 417,719 or No. 475,742. The non-felting fabric so obtained was neutralized and scoured and then run in a solution (1,250 parts) of commercial papain (0.30 part), sodium bisulphite (3.1 parts) and sodium acetate (3.1 parts) and the pH value of the solution was adjusted to 5.0 whilst in contact with the fabric by the addition of acetic acid.

- The temperature of the papain solution was raised to 65 C. and the fabric was circulated through the solution for two hours. At the end of this period, the fabric was neutralized, milled with soap for one hour, thoroughly rinsed with water and then with a 0.10 per cent solution of sodium hexametaphosphate. When dried it had a silky appearance and scroopy handle.

Example 4 The procedure was e same as that described in Example 3 up to and including the neutralization following the treatment with the papain solution. The neutralized fabric was then milled with soap for 15 minutes and then rinsed with water. After it had been partially dried and then pressed it had a silky appearance but was not scroopy. A

Example 5 A scoured worsted fabric (100 parts) was made non-felting by drying it until it contained 8 per cent of moisture and then treating it with a so lution of sulphuryl chloride in white spirit as described in British Patent No. 464,503. The nonfelting fabric so obtained was neutralized and then treated with a solution of papain and finished as described in Example 3 above. It had a silky appearance and scroopy handle.

It is to be understood that in the appended claims the term wool is used to include wool as loose fibres and also as manufactured goods such as yarns and fabrics; and also to include wool in blends of textile fibres and in manufactured goods containing other textile fibres.

We claim:

1. A process for imparting to wool a gloss resembling that of natural silk which comprises, treating .wool containing not more than 9 per cent of moisture with a non-aqueous agent selected from the group consisting of chlorine gas, sulphuryl chloride, organic hypochlorites and nitrosyl chloride to diminish the tendency oi the wool to felt, and subjecting the wool so treated to the action of a solution of papain containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment. I

2. A process as claimed in claim 1, wherein the papain solution also contains an. accelerator selected from the group consisting of sodium bisulphite, hydrogen sulphide, hydrocyanic acid and its water-soluble salts, water-soluble mercaptans, thiol acids and their water-soluble salts, sodium thiosulphate and sodium hydrosulphite.

3. A process as claimed in claim 1, wherein the papain solution also contains an accelerator selected from the group consisting of sodium bisulphite, hydrogen sulphide, hydrocyanic acid and its water-soluble salts, water-soluble mercaptans, thiol acids and their water-soluble salts, sodium thiosul'phate and sodium hydrosulphite. and further a substance selected from the group consisting of cysteine and a substance which gives rise to cysteine.

4. A process as claimed in claim 1, wherein the papain solution has a concentration of papain of about 0.025 per cent.

5. A process as claimed in claim 1, wherein the treatment with the papain solution is conducted at a temperature of 50-65 C.

6. A process for imparting to wool a gloss resembling that of natural silk which comprises. treating wool containing not more than 9 per cent of moisture with a non-aqueous agent selected from the group consisting of chlorine gas, sulphuryl chloride, organic hypochlorites and nitrosyl chloride to diminish the tendency of the wool to felt, and subjecting the wool so treated at a temperature of 50-65 C. t the action of a solution of papain having a concentration of about 0.025 per cent and containing an accelerator selected from the group consisting of sodium bisul-' phite, hydrogen sulphide, hydrocyanic-acid and its water-soluble salts, water-soluble mercaptans, thiol acids and their water-soluble salts, sodium thiosulphate and sodium hydrosulphite and also containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment.

7. A process as claimed in claim 6, wherein the accelerator is present in a quantity amounting to about 0.25 per cent of the weight of the papain solution. a

8. A process for imparting to wool a gloss resembling that of natural silk, which comprises treating wool containing not more than 9 per cent of moisture with chlorine gas to diminish the tendency of the wool to felt, and subjecting the wool so treated at a temperature of 50-65 C. to the action of a solution of papain having a concentration of about 0.025 per cent and containing a quantity of sodium bisulphite amounting to about 0.25 per cent of the weight of the solution of papai and also containing an electrolyte adapted to maintain the pH value of the soiution at approximately 5.0 during the treatment.

9. A process for imparting to wool a gloss resembling that of natural silk, which comprises treating wool containing not more than 9 per cent of moisture in the'form of fabric with a nonaqueous agent selected from the group consisting of chlorine gas, sulphuryl chloride, organic hypochlorites and nitrosyl chloride to the tendency of the wool to felt, and thereafter subjecting the treated fabric while it is being milled, to the action of a solution of papain containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment.

10. A process for imparting to wool a gloss resembling that of natural silk, which comprises treating wool containing not more than 9 per cent of moisture in the form of fabric with a nonqueous agent selected from the roup consisting of chlorine gas, sulphuryl chloride, organic hypochlorites and nitrosyl chloride to diminish the tendency of the wool to felt, then subjecting the treated fabric, while it is being milled, to the action of a solution of papain containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment, and subsequently milling the fabric in a soap solution.

11. A process for imparting to wool a gloss resembling that of natural silk, which comprises treating wool containing not more than 9 per cent of moisture with a non-aqueous agent selected from the group consisting of chlorine gas, sulphuryl chloride, organic hypochlorites and nitrosyl chloride to diminish the tendency of the wool to felt, subjecting the wool so treated to the action of a solution of papain containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment, and subsequently treating the wool with a solution of sodium hexametaphosphate.

12. A process for imparting to wool a gloss resembling that of natural silk, which comprises treating wool containing not more than 9 per cent of moisture with a non-aqueous agent selected from the group consisting of chlorine gas,

sulphuryl chloride, organic hypochlorites and nitrosyl chloride to diminish the tendency of the wool to felt, subjecting the wool so treated to the action of a solution of papain containing an electrolyte adapted to maintain the pH value of the solution at approximately 5.0 during the treatment, subsequently subjecting the material to light friction and pressure in the presence of a soap solution, rinsing the material insufficiently to remove all the soap, and subjecting it to heat and pressure whilst still damp.

HENRY PHILLIPS.

WILLIAM ROBERT MIDDLEBROOK.

ALFRED EDWARD HIGGINS. 

